Sadly, the GOG version lacks these, and while most (if not all) of these mods can be downloaded from Mod DB, this does provide a little extra hassle.
The easiest way to mod Empire At War is to own the Steam version, which has online multiplayer and integrated Workshop support. Here's a few mods that are strong in the Force. Petroglyph's hybrid RTS is still being actively supported, and the Steam version revived online multiplayer in 2017. Just assemble your fleets, kick open a hole in the enemy defences, and send down troops for a bit of terrestrial tactics. Playing a bit like a 4X strategy game in fast-forward, there's no base building and little micromanagement to be done in Empire At War. I bounced off Star Wars: Empire At War when it was new, but the siren call of modding beckoned me back. Every other Monday, Dominic gives you a reason to dust off one of your old games and dive into its mods with Modder Superior.